One of the reactions in a blast furnace used to reduce iron is shown above. how many grams of fe2o3 are required to produce 15.5 g of fe if the reaction occurs in the presence of excess co?

The balanced equation for the reaction is as follows
Fe₂O₃ + 3CO > 2Fe + 3CO₂
stoichiometry of Fe₂O₃ to Fe is 1:2
number of Fe moles formed - 15.5 g / 56 g/mol = 0.277 mol
if 2 mol of Fe are formed when 1 mol of Fe₂O₃ reacts 
then 0.277 mol of Fe are formed when -1/2 x  0.277 mol = 0.139 mol
number of Fe₂O₃ mol reacted - 0.139 mol 
mass of Fe₂O₃ required - 0.139 mol x 160 g/mol = 22.2 g
22.2 g of Fe₂O₃  required